Electronic – C standard libraries on bare metal

clibrary

I am mostly doing development on devices that have ported Linux so the standard C library provides lots of it's functionality through implementing system calls which have a standardised behaviour.

However for bare metal, there is no underlying OS. Is there a standard related to how a c library should be implemented or do you have to relearn peculiarity of a library implementations when you switch to new board which provides a different BSP?

Best Answer

Yes, there is a standard, simply the C standard library. The library functions do not require a "full blown" OS, or any OS at all, and there are a number of implementations out there tailored to "bare metal" code, Newlib perhaps being the best known.

Taking Newlib as an example, it requires you to write a small subset of core functions, mainly how files and memory allocation is handled in your system. If you're using a common target platform, chances are that someone already did this job for you.

If you're using linux (probably also OSX and maybe even cygwin/msys?) and type man strlen, it should have a section called something like CONFORMING TO, which would tell you that the implementation conforms to a specific standard. This way you can figure out if something you've been using is a standard function or if it depends on a specific OS.

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Electronic – Electronic Circuit Simulator API/Libraries

ummm spice does not really need an api ..... spice simulation file looks something like this

LPFILTER.CIR - SIMPLE RC LOW-PASS FILTER
*
VS  1   0   AC  1   SIN(0VOFF 1VPEAK   2KHZ)
*
R1  1   2   1K
C1  2   0   0.032UF
*
* ANALYSIS
.AC     DEC     5 10 10MEG
.TRAN   5US  500US
*
* VIEW RESULTS
.PRINT  AC  VM(2) VP(2)
.PRINT  TRAN    V(1) V(2)
*
.PROBE
.END

everything is driven by text files in the background and these files are passed to a pspice exe that normally does the rest. The spice engine itself is available with a BSD license so you can tweak it yourself.

Most commercial offerings offer schematic entry, parts libraries and output plotting options.

You can do away with this be passing in a netlist file with the simulation details to an spice engine and get back a text file of results.

So no real api just a command line driven app. Of course you can get the source code and compile it into you own application.

check out wikipedia for more details.

Electronic – CADSOFT EAGLE libraries searching best practices

What is the best practice to find libraries for Eagle?

First you must be sure that your device is not in eagle libraries using good search, For example if you want to add 7805 5v regulator, You must search like this: *7805* That because certain manufacturer have their own extension that you don't know.
If you didn't find your device or reasonable alternative (you can use for example atmega8 device instead of atmega328 device.Try to use famous public libraries produced by:

SparkFun Eagle Lib - AdaFruit Eagle Lib - Dangerous Prototype Eagle Lib - Element14 Eagle Cad Lib Search

Also a good practice is to memorize if the part you want to use is used in previous open source board, If answer is Yes then go and export used parts there from ULP.
When you build your own library keep in mind that there is a reference library in eagle called Ref-packages.lib that have most of electronics packages which make create new libraries much easier.

How can I be sure that the library I found is a good quality?

Just print footprint on a paper and make sure that every thing is OK, or you can make sure from eagle that physical footprint is typical to part description from datasheet.

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Related Solutions

Electronic – Electronic Circuit Simulator API/Libraries

Electronic – CADSOFT EAGLE libraries searching best practices

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